JPH102912A - Semiconductor-acceleration sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an integrated type semiconductor-acceleration sensor, which can be manufactured by a minute semiconductor manufacturing process and has the high shock resistance and the function of high sensibility as a compact unitary body shape and the manufacturing method thereof. SOLUTION: In this sensor, a semiconductor substrate 1, a first nitride film 2, a first polysilicon layer 3, a second nitride film 4, a second polysilicon layer 5, a third nitride film 6 and a third polysilicon layer 7 are sequentially formed. In a space part 17, which is surrounded and sealed by the first niteride film 2, the first polysilicon layer 3, the second niteride film 4, the second polysilicon layer 5, the third niteride film 6 and the third polysilicon layer 7 and a part of the second polysilicon layer 5 is formed as a movable part 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact, highly shock-resistant semiconductor acceleration sensor which is mounted on, for example, an automobile or equipment and detects acceleration at the time of a collision of an automobile or acceleration of equipment, and a method of manufacturing the same. It is about.

[0002]

2. Description of the Related Art A capacitance type acceleration sensor and a strain gauge type pressure sensor are mounted on a vehicle and used for controlling a vehicle body and an engine of the vehicle. As a specific example of the acceleration sensor, for example, Japanese Patent Laid-Open No. 2-134570
There is a semiconductor acceleration sensor disclosed in Japanese Unexamined Patent Application Publication No. H10-209,873.

FIG. 29 is a view showing the above-mentioned Japanese Patent Application Laid-Open No. Hei 2-13457.
FIG. 1 is a cross-sectional view showing a semiconductor acceleration sensor disclosed in Japanese Patent Application Laid-Open No. 0-104, in which reference numerals 41, 42 and 43 denote silicon substrates, which are directly bonded by anodic bonding via oxide films 44 and 45 for electric insulation. Have been. 46 and 4
7 is a silicon beam and a movable electrode, respectively.
The silicon substrate 42 is formed in the space 48 by etching.

Next, the operation will be described. In the conventional semiconductor acceleration sensor shown in FIG. 29, the interelectrode capacitance of a gap 48 formed between the movable electrode 47 and the silicon substrate 41 and the silicon substrate 43 according to the magnitude of the acceleration acting on the semiconductor acceleration sensor. Changes. Based on the change in the interelectrode capacitance, the magnitude of the acceleration applied to the device equipped with the semiconductor acceleration sensor is detected.

[0005]

Since the conventional semiconductor acceleration sensor is configured as described above, the movable electrode 47 is provided.
In addition to the silicon substrate 42 for forming the
Silicon substrates 41 and 43 for the fixed electrode which are arranged and adhered to the upper and lower portions of the silicon substrate 2 are separately required. In addition to the normal semiconductor manufacturing process, the silicon substrate 41 and the silicon substrate 43 and the silicon substrate 42 A separate processing process is required to join the gaps, which increases the manufacturing time and the manufacturing cost, and also increases the silicon substrates 41, 42,
There was a problem that the movable electrode 47 was easily damaged during the bonding process of No. 43 and the yield was low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can be manufactured by a semiconductor microfabrication manufacturing process at a time, has high impact resistance, is small, and has a function of high sensitivity. It is an object of the present invention to obtain a body-shaped semiconductor acceleration sensor and a method of manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a semiconductor acceleration sensor, comprising: a first insulating layer, a first polysilicon layer, a second insulating layer, a second polysilicon layer, a third insulating layer, and a second insulating layer. Three polysilicon layers are formed in an integral structure, and a void surrounded by the first insulating layer, the first polysilicon layer, the second insulating layer, the second polysilicon layer, the third insulating layer, and the third polysilicon layer is A part of the second polysilicon layer is formed as a movable part in the gap obtained by sealing, and therefore has a small size and a high impact resistance function, and has a function of the acceleration applied to the semiconductor acceleration sensor. The change is detected by the movable portion with high sensitivity.

According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor acceleration sensor, comprising: a first insulating layer, a first polysilicon layer,
A first oxide film, a second insulating layer, a second polysilicon layer, a second dioxide film, a third insulating layer and a third polysilicon layer are sequentially manufactured by a semiconductor microfabrication manufacturing process, and the first oxide film and the second dioxide film are formed. Eliminating all at once by etching to form a gap, forming a movable part, and finally sealing the etching hole and sealing the gap to produce an integrated semiconductor acceleration sensor with high yield and high efficiency It is.

According to a third aspect of the present invention, there is provided a semiconductor acceleration sensor wherein the semiconductor acceleration sensor and the integrated circuit are formed on the same semiconductor substrate and are integrated with the integrated circuit. It is input immediately to efficiently execute signal processing such as amplification.

According to a fourth aspect of the present invention, the semiconductor acceleration sensor detects the magnitude of the capacitance applied between the movable electrode and the fixed electrode, thereby detecting the magnitude of the acceleration applied to the semiconductor acceleration sensor. Things.

According to a fifth aspect of the present invention, in the semiconductor acceleration sensor, the movable portion is supported by two bridges, thereby detecting the magnitude of the acceleration applied to the semiconductor acceleration sensor with high sensitivity. .

According to a sixth aspect of the present invention, in the semiconductor acceleration sensor, a left movable electrode and a right movable electrode are formed on the second polysilicon layer, and the first polysilicon corresponds to the left movable electrode and the right movable electrode. A left fixed electrode and a right fixed electrode are respectively formed in the layer, a central portion of the movable electrode is supported by the second insulating layer, and the magnitude of the acceleration applied to the semiconductor acceleration sensor by the left and right movable electrodes and the left and right fixed electrodes is determined. It detects with high sensitivity.

According to a seventh aspect of the present invention, in the semiconductor acceleration sensor, the four ends of the movable electrode are supported by the plurality of support portions, and thereby the magnitude of the acceleration applied to the semiconductor acceleration sensor can be highly sensitive. Is to be detected.

In the semiconductor acceleration sensor according to the present invention, an upper fixed electrode and a lower fixed electrode are formed in the third polysilicon layer and the first polysilicon layer corresponding to the upper and lower sides of the movable electrode, respectively. Detects the change in the magnitude of the capacitance generated between the movable electrode and the upper fixed electrode, and between the movable electrode and the lower fixed electrode, and detects the magnitude of the acceleration applied to the semiconductor acceleration sensor with high sensitivity. Is to be detected.

In the semiconductor acceleration sensor according to the present invention, a diffusion resistance portion is formed in a part of the movable portion, and the resistance is applied to the semiconductor acceleration sensor by measuring a change in the resistance value of the diffusion resistance portion. The magnitude of the acceleration is detected with high sensitivity.

According to a tenth aspect of the present invention, in the semiconductor acceleration sensor, the diffusion resistance portion is formed in a thin portion having a thickness smaller than the thickness of the second polysilicon layer in which the diffusion resistance portion is not formed. This is to detect the magnitude of the acceleration applied to the semiconductor acceleration sensor with high sensitivity.

In the semiconductor acceleration sensor according to the present invention, a lower fixed electrode is formed inside the first polysilicon layer, a movable electrode is formed inside the second polysilicon layer, and a third polysilicon layer is formed. An upper fixed electrode is formed inside, furthermore, a wiring is formed by diffusing impurities in the first polysilicon layer, the second polysilicon layer and the third polysilicon layer, and between the movable electrode and the upper fixed electrode, Further, by detecting a change in the magnitude of the capacitance generated between the movable electrode and the lower fixed electrode through a wiring, the magnitude of the acceleration applied to the semiconductor acceleration sensor is detected with high sensitivity.

According to a twelfth aspect of the present invention, there is provided a semiconductor acceleration sensor according to the present invention, wherein a voltage is applied between a movable electrode and a fixed electrode which is generated by applying a voltage to a drive electrode formed apart from the fixed electrode in the first polysilicon layer. The self-diagnosis is performed by detecting a change in the capacitance to detect whether or not the movable electrode is damaged.

According to a thirteenth aspect of the present invention, in the semiconductor acceleration sensor, a diffusion resistance portion is formed in the second polysilicon layer, and a voltage is applied to a fixed electrode (drive electrode) formed in the first polysilicon layer. The self-diagnosis is performed by detecting the presence or absence of damage to the movable electrode by measuring the resistance value of the diffusion resistance portion generated in step (1).

According to a fourteenth aspect of the present invention, in the semiconductor acceleration sensor, a driving electrode is formed in the third polysilicon layer, and a movable electrode generated by applying a voltage to the driving electrode and the first polysilicon layer are formed. The self-diagnosis is performed by detecting the change of the capacitance between the formed fixed electrode and the movable electrode by detecting the damage of the movable electrode.

According to a fifteenth aspect of the present invention, in the semiconductor acceleration sensor, a lower fixed electrode is formed inside the first polysilicon layer, a movable electrode is formed inside the second polysilicon layer, and a third polysilicon layer is formed. An upper fixed electrode is formed in the inside, and furthermore, an impurity is diffused into the first polysilicon layer, the second polysilicon layer, and the third polysilicon layer to form a wiring, and the lower fixed electrode is further fixed in the first polysilicon layer. By detecting the change in capacitance between the movable electrode and the upper fixed electrode and the capacitance between the movable electrode and the lower fixed electrode caused by applying a voltage to the drive electrode formed apart from the electrode, damage to the movable electrode is detected. The self-diagnosis is performed by detecting the presence or absence.

According to a sixteenth aspect of the present invention, in the semiconductor acceleration sensor chip, the semiconductor acceleration sensor or the semiconductor acceleration sensor and an integrated circuit are formed on the same semiconductor substrate.
The semiconductor acceleration sensor is connected to the lead frame via a wire bond, the whole is covered with a resin mold, sealed and manufactured in an integrated structure in the same package, so that it is small and has high impact resistance. Things.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a sectional view showing a semiconductor acceleration sensor according to Embodiment 1 of the present invention.
1 is a semiconductor silicon substrate (semiconductor substrate), 2 is a first nitride film (first insulating layer) as an insulating layer formed on the surface of the semiconductor silicon substrate 1, and 3 is formed on the first nitride film 2. The first polysilicon layer, 4 is a second nitride film (second insulating layer) formed on the first polysilicon layer 3, 5 is the second polysilicon layer formed on the second nitride film 4, and 5a is It is a movable part that is a part of the second polysilicon layer 5 and the periphery of which is surrounded by the gap 171. When acceleration is applied to the semiconductor acceleration sensor, the movable portion 5a is displaced according to the magnitude of the acceleration. 6 is a third nitride film (third insulating layer) formed on the second polysilicon layer 5, 7 is a third polysilicon layer formed on the third nitride film 6, and 8 is a third polysilicon layer. 7 is a sealing portion in which the etching hole formed in 7 is filled with polysilicon.

In the semiconductor acceleration sensor according to the first embodiment, unlike the conventional semiconductor acceleration sensor, the second polysilicon layer forming the movable portion is formed without using a special manufacturing process such as an anodic bonding process. 2 to 4, the first polysilicon layer 13, the second polysilicon layer 1
6 and the third polysilicon layer 19 are sequentially formed in a semiconductor manufacturing process, and the first oxide film 14 and the second dioxide film 17 are removed by etching to collectively form the movable portion 5.
Since a is formed, the manufacturing process is not complicated, and it is small and has a function resistant to impact.

Next, the operation will be described. In the semiconductor acceleration sensor shown in FIG. 1, when the acceleration in the direction of the arrow is applied to the semiconductor acceleration sensor, the position of the movable portion 5a is displaced according to the magnitude of the acceleration. This displacement changes the capacitance between the first polysilicon layer 3 and the third polysilicon layer 7 and the second polysilicon layer 5, and converts the change in the capacitance into an electric signal, thereby accelerating the acceleration. Detect the size of.

Next, a method of manufacturing the semiconductor acceleration sensor according to the first embodiment of the present invention will be described. 2 to 4
FIG. 3 is an explanatory diagram illustrating a method for manufacturing the semiconductor acceleration sensor illustrated in FIG. 1. The numbers in parentheses indicate the components of the semiconductor acceleration sensor shown in FIG.

First, a semiconductor silicon substrate (semiconductor substrate)
A first nitride film (first insulating layer) 12 on the surface of 11 (1)
(2) is deposited (FIG. 2A), and then the first nitride film 1 is deposited.
2 is deposited on the first polysilicon layer 13 (3) (FIG. 2B). Then, a part of the first polysilicon layer 13 is removed by etching (FIG. 2C).

Next, a first oxide film 14 is deposited on the first nitride film 12 and the first polysilicon layer 13 (FIG. 2).
(D)), a part of the first oxide film 14 is removed by etching to form the void 171 shown in FIG. 1 (FIG. 2)
(E)). Next, a second nitride film (second insulating layer) 15 (4)
Is deposited on the first polysilicon layer 13 to form the first oxide film 1.
4 and the surface of the second nitride film 15 are partially removed by etching. Thereby, the surface portions of the first oxide film 14 and the second nitride film 15 are planarized (FIG. 2F).

Next, a second polysilicon layer 16 (5) is deposited on the first oxide film 14 and the second nitride film 15 (FIG. 3).
(A)). Then, a part of the second polysilicon layer 16 is removed by etching to form the movable portion 5a (FIG. 3).
(B)). Then, a second dioxide film 17 is deposited on the first oxide film 14 and the second polysilicon layer 16 (FIG. 3).
(C)) The second dioxide film 1 is formed to form the voids 171.
7 is removed by etching (FIG. 3D).

Next, a third nitride film (third insulating layer) 18
(6) is deposited on the second polysilicon layer 16, and the third nitride film 18 on the surface of the second dioxide film 17 is removed by etching. Thereby, the surfaces of the second dioxide film 17 and the third nitride film 18 are flattened (FIG. 3E).

Next, a third polysilicon layer 19 (7) is deposited on the surfaces of the second dioxide film 17 and the third nitride film 18 (FIG. 4A). Then, an etching hole 20 is formed in a part of the third polysilicon layer 19 (FIG. 4).
(B)). The first oxide film 1 is etched through the etching hole 20 by using, for example, a fluoric acid vapor etching method.
4 and the second dioxide film 17 are removed (FIG. 4C). As a result, the fixed electrode and the movable electrode formed of the first polysilicon layer 13, the second polysilicon layer 16, and the third polysilicon layer 19 are collectively formed. Next, polysilicon is deposited in the etching hole 20 to form the void 17.
1 to form a sealing portion 8 (FIG. 4D).

As described above, according to the semiconductor acceleration sensor and the method of manufacturing the same according to the first embodiment, the first nitride film 12, the first polysilicon layer 13, the first oxide film 14, the second polysilicon layer 16, The second dioxide film 17 and the third polysilicon layer 19 can be continuously deposited on the semiconductor silicon substrate 11. Further, the first oxide film 14 and the second dioxide film 17 are removed through the etching hole 20 by the fluoric acid vapor etching method, so that the movable portion 5a whose position changes and the capacitance changes in response to the change in acceleration. To the second polysilicon layer 1
6, and then the etching hole 20 is closed with polysilicon to form an integrated structure of the semiconductor acceleration sensor, and a compact, high-impact semiconductor acceleration sensor can be obtained.

Embodiment 2 FIG. 5, 6, and 7
FIG. 5 is a sectional view showing a semiconductor acceleration sensor according to a second embodiment of the present invention. In FIG. 5, reference numeral 21 denotes a CMOS circuit unit (integrated) formed on the same semiconductor silicon substrate 11 as the semiconductor acceleration sensor shown in FIG. In FIG. 6, reference numeral 22 denotes a bipolar circuit section (integrated circuit) formed on the same semiconductor silicon substrate 11 as the semiconductor acceleration sensor shown in FIG. FIG. 7 is a cross-sectional view when the semiconductor acceleration sensor shown in FIG. 1, the CMOS circuit part 21 shown in FIG. 5, and the bipolar circuit part 22 shown in FIG. 6 are formed on the same semiconductor silicon substrate 11. The same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the second embodiment,
The CMOS circuit section 21 and the bipolar circuit section 22 are formed on the semiconductor silicon substrate 11 before forming the semiconductor acceleration sensor shown in FIG. 1, and then the semiconductor acceleration sensors are collectively formed on the same semiconductor silicon substrate 11. .

Next, the operation will be described. The magnitude of the acceleration applied to the semiconductor acceleration sensor is detected, and the detection result is output to the CMOS circuit unit 21 and the bipolar circuit unit 22 as an output signal. The CMOS circuit unit 21 and the bipolar circuit unit 22 input, amplify and digitally process the output signal from the semiconductor acceleration sensor, and then transmit it to another device (not shown).

As described above, according to the semiconductor acceleration sensor of the second embodiment, the semiconductor acceleration sensor of the first embodiment shown in FIG. Since it is integrally formed on the top, an output corresponding to the acceleration from the semiconductor acceleration sensor can be immediately input and amplified, and a small and highly shock-resistant semiconductor acceleration sensor capable of digital processing can be obtained. Costs can be reduced.

Embodiment 3 8, 9 and 10 are a sectional view (a) and a plan view (b) showing a semiconductor acceleration sensor according to a third embodiment of the present invention. In FIG. A fixed electrode formed in a part, 24 is a movable part formed in a part of the second polysilicon layer 16, 24a is a support part of the movable part 24, 24b is provided between the support part 24a and the movable part 24 Cross-linking. In FIG. 9, reference numeral 24c denotes a left movable electrode formed at the left end of the movable portion 24, 24d denotes a right movable electrode which is a movable electrode formed at the right end of the movable portion 24, and 23a and 23b denote left movable electrodes 24c and right. A left fixed electrode and a right fixed electrode are respectively formed corresponding to the movable electrode 24d. Further, in FIG. 10, reference numeral 24f denotes a movable electrode, and 24g denotes four support portions for supporting the movable electrode 24f. FIG.
The same components as those of the first embodiment shown in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the third embodiment, two bridges 24b are provided between the movable part 24 and the support part 24a, and the movable electrode 24f is supported only at the central part of the movable part 24, so that the left and right sides are supported. A semiconductor acceleration sensor having a structure in which a left movable electrode 24c and a right movable electrode 24d are provided and a movable electrode 24f is supported by a plurality of support portions 24g is provided to further improve the sensitivity of the acceleration sensor.

Next, the operation will be described. In the semiconductor acceleration sensor shown in FIG. 8, a bridge 24b is provided in the vicinity of the support portion 24a of the movable portion 24, and the movable portion 24 detects a change in the magnitude of the acceleration applied to the semiconductor acceleration sensor by moving the fixed electrode 23 with the fixed electrode 23. The change is detected as a change in the capacitance generated between the semiconductor acceleration sensor and the unit 24, and thereby the magnitude of the acceleration applied to the semiconductor acceleration sensor is detected. Further, in the semiconductor acceleration sensor having the configuration shown in FIG. 9, the movable portion 24 is supported only at the center of the movable portion 24, and the left movable electrode 24c is formed on the left end portion and the right movable electrode 24d is formed on the right end portion. Movable electrode 24c
A left fixed electrode 23a and a right fixed electrode 23b are formed corresponding to the right movable electrode 24d. Left fixed electrode 2
3a, a change in capacitance between the right fixed electrode 23b, the left movable electrode 24c, and the right movable electrode 24d is detected to detect the magnitude of the acceleration applied to the semiconductor acceleration sensor.

In the semiconductor acceleration sensor shown in FIG. 10, the movable electrode 24f of the movable portion 24 is connected to four support portions 24g.
And detects a change in the capacitance generated between the fixed electrode 23 and the movable electrode 24f, thereby detecting the magnitude of the acceleration applied to the semiconductor acceleration sensor with higher sensitivity.

As described above, according to the semiconductor acceleration sensor of the third embodiment, the bridge 24b is provided near the supporting portion of the movable portion 24, and the movable portion 24 is supported only at the center of the movable portion 24. And left fixed electrode 23a, right fixed electrode 23b
And a left movable electrode 24c and a right movable electrode 24d. Further, the movable electrode 24f of the movable portion 24 is
4 g, the influence of the torsion of the movable portion 24 can be reduced, and the change in acceleration applied to the semiconductor acceleration sensor can be determined based on the change in capacitance generated between the fixed electrode and the movable electrode. Since the detection can be performed with high sensitivity, the sensitivity of the acceleration sensor can be improved, and a compact and high-impact semiconductor acceleration sensor can be obtained.

Embodiment 4 FIG. 11 is a sectional view showing a semiconductor acceleration sensor according to Embodiment 4 of the present invention (a).
FIG. 23B shows a lower fixed electrode formed in the first polysilicon layer 13;
Is a movable part formed on a part of the second polysilicon layer 16,
25 is an upper fixed electrode formed in the third polysilicon layer 19. The same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the fourth embodiment, the third polysilicon layer 19 is fixed on the upper side of the first polysilicon layer 13 as the lower fixed electrode 23 ′, the second polysilicon layer 16 as the movable portion 24, and the upper portion. It is formed as an electrode 25, and the magnitude of the acceleration applied to the semiconductor acceleration sensor is determined from the change in the capacitance generated between the movable portion 24 and the upper fixed electrode 25 and between the movable portion 24 and the lower fixed electrode 23 '. It is intended to improve the sensitivity of detecting and detecting acceleration.

Next, the operation will be described. The magnitude of the acceleration applied to the semiconductor acceleration sensor is determined by the lower fixed electrode 2
The detection is performed based on a change in capacitance generated both between 3 ′ and the movable section 24 and between the upper fixed electrode 25 and the movable section 24.

As described above, according to the semiconductor acceleration sensor of the fourth embodiment, the lower fixed electrode 23 'and the movable portion 2
4, and the magnitude of the acceleration applied to the semiconductor acceleration sensor can be more sensitively detected based on the change in the capacitance generated both between the upper fixed electrode 25 and the upper fixed electrode 25 and the movable portion 24. The sensitivity of the semiconductor acceleration sensor can be further improved, and a small-sized semiconductor acceleration sensor having high impact resistance can be obtained.

Embodiment 5 FIG. 12, 13, 14,
FIG. 15 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a fifth embodiment of the present invention. In FIG. 12, reference numeral 26 denotes a movable electrode formed on the second polysilicon layer 16, and 26a and 26b. Denotes a plurality of beam portions formed on a part of the movable electrode 26, and 27, 27a to 27d denote diffusion resistance portions formed by diffusing impurities into the movable electrode 26. The same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the fifth embodiment, the movable electrode 2 formed in the second polysilicon layer 16
6, a diffusion resistance portion 27 whose resistance value changes according to the magnitude of the acceleration applied to the semiconductor acceleration sensor,
27a to 27d are formed, and the diffusion resistance portions 27, 27a are formed.
The magnitude of the applied acceleration is detected with high sensitivity by measuring the resistance value of .about.27d.

Next, the operation will be described. In the semiconductor acceleration sensor shown in FIG. 12, a diffusion resistance portion 27 whose resistance value changes according to the magnitude of acceleration applied to a part of the movable electrode 26 formed on the second polysilicon layer 16 is formed. I have. By forming the diffusion resistance portion 27 in a part of the movable electrode 26, the magnitude of the acceleration applied to the semiconductor acceleration sensor is detected with high sensitivity.

In the semiconductor acceleration sensor shown in FIG. 13, the vicinity of the support portion of the movable electrode 26 is formed as a bridge structure, and a diffusion resistance portion 27 is formed in the bridge portion, and the resistance is applied by measuring a change in the resistance value. Detects the magnitude of acceleration with high sensitivity.

In the semiconductor acceleration sensor shown in FIG. 14, the vicinity of the supporting portion of the movable electrode 26 is formed by a plurality of beams 26a and 26b, and the diffusion resistance 27 is provided in the beams 26a and 26b.
The beam portions 26a and 26b work so that the movable electrode 26 is not affected by torsion and the like, and detect the magnitude of the applied acceleration with high sensitivity.

In the semiconductor acceleration sensor shown in FIG. 15, a plurality of diffusion resistances, that is, four diffusion resistance parts 27a, 27b, 27c, 27d are formed near the support of the movable electrode 26. These diffusion resistance portions 27a, 27b, 27c, 27
By forming a bridge circuit with d, the magnitude of the applied acceleration is detected with higher sensitivity.

FIG. 16 is an explanatory diagram showing a manufacturing process for forming mainly the diffusion resistance portion 27 in the movable electrode 26 in the semiconductor acceleration sensor according to the fifth embodiment shown in FIGS. 16A shows a state before the impurity implantation, and FIG. 16B shows a state after the impurity implantation. In addition,
Other manufacturing processes are the same as those of the first embodiment shown in FIGS. First, as shown in FIG. 16A, after the second polysilicon layer 16 is etched to form the movable electrode 26,
A resist film 28 is applied to the surfaces of the first oxide film 14 and the second polysilicon layer 16. Then, after removing the resist film 28 at a portion corresponding to the position where the diffusion resistance portion 27 is formed by etching, for example, boron (B),
Impurities such as phosphorus (P), arsenic (As), and antimony (Sb) are implanted to form the diffusion resistance portion 27.

As described above, according to the semiconductor acceleration sensor of the fifth embodiment, the diffusion resistance whose resistance value changes in part of the movable electrode 26 in accordance with the magnitude of the acceleration applied to the semiconductor acceleration sensor. The portions 27, 27a to 27d are formed to detect the magnitude of the acceleration applied to the semiconductor acceleration sensor with high sensitivity, and the vicinity of the supporting portion of the movable electrode 26 is formed by a plurality of beams 26a, 26b. So movable electrode 2
The semiconductor acceleration sensor 6 is less susceptible to torsion and the like, and a small and high-impact semiconductor acceleration sensor can be obtained.

Embodiment 6 FIG. FIG. 17 is a sectional view showing a semiconductor acceleration sensor according to a sixth embodiment of the present invention. In the figure, reference numeral 29 denotes a thin wall formed below a diffusion resistance section 27 provided near a support section in a movable electrode 26. Department. The same components as those of the fifth embodiment shown in FIGS. 12 to 16 are denoted by the same reference numerals, and the description thereof will not be repeated.

In the semiconductor acceleration sensor according to the sixth embodiment, the diffusion resistance portion 27 provided in a part of the movable electrode 26 is provided.
The thickness of the applied acceleration is detected with higher sensitivity by forming the thin portion 29 at the lower part of.

Next, the operation will be described. Movable electrode 26
The magnitude of the applied acceleration is detected with higher sensitivity by the presence of the thin portion 29 formed below the diffusion resistance portion 27 provided in the vicinity of the support portion.

FIG. 18 is an explanatory view showing a manufacturing process of the semiconductor acceleration sensor having the movable electrode 26 having the thin portion 29 shown in FIG. As shown in FIG. 18A, a first oxide film 14 is deposited on a part of the surface of the first nitride film 12 and the first polysilicon layer 13, and then a void 17 is formed.
A portion of the first oxide film 14 is removed by etching so as to leave a portion that becomes 1. After that, a second nitride film 15 is deposited on the surface of the first polysilicon layer 13. Then, the surface of the second nitride film 15 (not shown) deposited on the surface of the first oxide film 14 is etched so that the surfaces of the first oxide film 14 and the second nitride film 15 become flat. Do. After that, the entire first oxide film 14 is etched so as to leave a portion corresponding to the thin portion 29 on the first oxide film 14, and the trapezoidal shape 1 is formed.
41 are formed (FIG. 18B). Further, the second polysilicon layer 16 is formed by the first oxide film 14 and the second nitride film 15.
(FIG. 18C).

Thereafter, the movable electrode 26 is formed by etching the second polysilicon layer 16 (FIG. 18D), and then a resist film 28 is formed on the second polysilicon layer 16 and the second polysilicon layer 16. It is applied on the movable electrode 26 as a part. After that, the resist film 28 at a portion corresponding to the diffusion resistance portion 27 is removed, and an impurity is implanted into the diffusion resistance portion 2.
7 is formed (FIG. 18E). The subsequent manufacturing process is the same as the manufacturing process of the semiconductor acceleration sensor according to the first embodiment shown in FIGS.

As described above, according to the semiconductor acceleration sensor of the sixth embodiment, since the thin portion 29 is formed below the diffusion resistance portion 27, the magnitude of the applied acceleration can be detected with higher sensitivity. And a semiconductor acceleration sensor having a small size and high impact resistance can be obtained.

Embodiment 7 FIG. 19 and 21 are a sectional view (a) and a plan view (b) showing a semiconductor acceleration sensor according to Embodiment 7 of the present invention.
30 is a movable electrode formed on a part of the second polysilicon layer 16, 31 is a lower fixed electrode formed on a part of the first polysilicon layer 13, and 32 and 33 are movable electrodes 3 respectively.
0 and a signal for outputting a signal from the lower fixed electrode 31 to an external device (not shown).
3, the second polysilicon layer 16, the third polysilicon layer 19
Is formed by diffusing impurities into the substrate. 34 is an upper fixed electrode formed in the third polysilicon layer 19. The same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the seventh embodiment, impurities are diffused into first polysilicon layer 13 and second polysilicon layer 16 to form upper fixed electrode 34 and lower fixed electrode 31, movable electrode 30 and wiring 32. , 33 are formed to have high shock resistance and detect a change in acceleration applied to the semiconductor acceleration sensor with high sensitivity.

Next, the operation will be described. The change in the acceleration applied to the semiconductor acceleration sensor is detected with high sensitivity by detecting the change in the capacitance generated between the movable electrode 30 and the upper fixed electrode 34 and between the movable electrode 30 and the lower fixed electrode 31 with high sensitivity. Output to an external device (not shown) via 32 and 33.

FIGS. 20 and 22 correspond to FIGS.
FIG. 28 is an explanatory diagram showing the manufacturing process of the semiconductor acceleration sensor according to the seventh embodiment shown in FIG. FIG. 20 shows the lower fixed electrode 3.
FIG. 20 is an explanatory view showing a manufacturing process up to the formation of the upper fixed electrode 34 by diffusing impurities into the third polysilicon layer 19. The same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 20A, a first polysilicon layer 13 is deposited on a first nitride film 12 deposited on a semiconductor silicon substrate 11.
Is partially removed by etching. Next, an impurity is diffused into a part of the first polysilicon layer 13 to form the lower fixed electrode 3.
1 (FIG. 20B). Further, after the first oxide film 14 is deposited on the first nitride film 12, the first polysilicon layer 13, and the lower fixed electrode 31 in the first polysilicon layer 13 (FIG. 20 (c)), The first oxide film 14 was removed by etching so as to leave a portion, and then the second nitride film 15 was deposited on the first polysilicon layer 13 and the lower fixed electrode 31, and was deposited on the first oxide film 14. The second nitride film 15 is removed by etching. Further, the surfaces of the first oxide film 14 and the second nitride film 15 are flattened by etching. Then, a second polysilicon layer 16 is deposited on the planarized first oxide film 14 and second nitride film 15 (FIG. 20D).

Next, in order to form a movable portion which is the movable electrode 30, a part of the second polysilicon layer 16 is removed by etching. Thereafter, impurities are diffused in the second polysilicon layer 16 to form the movable electrode 30 in the second polysilicon layer 16 (FIG. 20E). Thereafter, a third nitride film 18 is deposited on the surface of the second polysilicon layer 16 and the movable electrode 30.

Next, as shown in FIG. 22, after a third polysilicon layer 19 is deposited on the surface of the third nitride film 18 (FIG. 22 (a)), impurities are contained in the third polysilicon layer 19. Is formed to form an upper fixed electrode 34 (FIG. 22B). Next, an etching hole 20 is formed in the third polysilicon layer 19 (FIG. 22C), and the first oxide film 14 and the second oxide film 14 are formed through the etching hole 20 using, for example, a fluoric acid vapor etching method. The dioxide film 17 is removed (FIG. 22D).

Thus, the lower fixed electrode 31, the upper fixed electrode 34, and the movable electrode 30 formed of the first polysilicon layer 13, the second polysilicon layer 16, and the third polysilicon layer 19 are formed at a time. . Thereafter, polysilicon is deposited in the etching hole 20 to seal the gap 171 to form a semiconductor acceleration sensor (FIG. 22E).

As described above, according to the semiconductor acceleration sensor of the seventh embodiment, the impurities are diffused into first polysilicon layer 13 and second polysilicon layer 16 and upper fixed electrode 34 and lower fixed electrode 31 are diffused. And the movable electrode 30 and the wirings 32 and 33 are formed, the impact resistance is high, the change in acceleration applied to the semiconductor acceleration sensor can be detected with high sensitivity, and the semiconductor device is small and has high impact resistance. An acceleration sensor can be obtained.

Embodiment 8 FIG. FIG. 23 is a sectional view showing a semiconductor acceleration sensor according to an eighth embodiment of the present invention.
And a plan view (b), in which 31 is a lower fixed electrode formed on a part of the first polysilicon layer 13, 3
Reference numeral 5 denotes a drive electrode, which is formed separately from the lower fixed electrode 31. The same components as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the eighth embodiment, when a voltage is applied to the drive electrode 35, an electrostatic force is generated between the drive electrode 35 and the movable electrode 30, and the movable electrode 30 is moved according to the magnitude of the electrostatic force. Is displaced. The lower fixed electrode 31 detects the amount of this displacement, and has a self-diagnosis function of determining in advance whether the movable electrode 30 is damaged.

Next, the operation will be described. A lower fixed electrode 31 and a drive electrode 35 are formed in the first polysilicon layer 13, a movable electrode 26 is formed in the second polysilicon layer 16, and a movable electrode 30 is formed in the movable electrode 26. For example, when a voltage is applied to the drive electrode 35 in order to self-diagnose the function of the semiconductor acceleration sensor, the drive electrode 3
An electrostatic force is generated between the movable electrode 5 and the movable electrode 30, and the movable electrode 30 is displaced according to the magnitude of the electrostatic force. The amount of this displacement is detected by the lower fixed electrode 31 to determine whether the movable electrode 30 is damaged.

As described above, according to the semiconductor acceleration sensor of the eighth embodiment, when a voltage is applied to the drive electrode 35, an electrostatic force is generated between the movable electrode 30 and the drive electrode 35,
The displacement of the movable electrode 26 caused by the electrostatic force is detected by the lower fixed electrode 31 so that the presence or absence of damage to the movable electrode 26 can be self-diagnosed, and a compact and high-impact semiconductor acceleration sensor can be obtained.

Embodiment 9 FIG. 24 is a sectional view showing a semiconductor acceleration sensor according to Embodiment 9 of the present invention.
And a plan view (b). 1 to 4 and FIG.
Components similar to those of the first, fifth, and eighth embodiments shown in FIG. 23 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the ninth embodiment, an electrostatic force is generated by applying a voltage to the drive electrode 35, and the movable electrode 26 is displaced by the electrostatic force. Is detected by the diffusion resistance section 27 to detect whether or not the movable electrode 26 is damaged.

Next, the operation will be described. A drive electrode 35 is formed in the first polysilicon layer 13, a movable electrode 26 is formed in the second polysilicon layer 16, and a movable electrode 30 is formed in the movable electrode 26. For example, when a voltage is applied to the drive electrode 35 in order to self-diagnose the function of the semiconductor acceleration sensor, an electrostatic force is generated between the drive electrode 35 and the movable electrode 30, and the movable electrode 30 is moved according to the magnitude of the electrostatic force. Displace. The amount of this displacement is determined by the diffusion resistance 27
Is detected to determine whether the movable electrode 30 is damaged.

As described above, according to the semiconductor acceleration sensor of the ninth embodiment, when a voltage is applied to the drive electrode 35, an electrostatic force is generated between the movable electrode 30 and the drive electrode 35,
The diffusion resistor 27 detects the displacement of the movable electrode 30 caused by the electrostatic force, and the self-diagnosis of the presence or absence of damage to the movable electrode 26 can be performed. Further, a small-sized semiconductor acceleration sensor having high impact resistance can be obtained.

Embodiment 10 FIG. FIG. 25 is a sectional view (a) and a plan view (b) showing a semiconductor acceleration sensor according to Embodiment 10 of the present invention.
Is a drive electrode formed on a part of the third polysilicon layer 19. The same components as those in Embodiments 1 and 7 shown in FIGS. 1 to 4 and FIG. 21 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the ninth embodiment, when a voltage is applied to drive electrode 235, an electrostatic force is generated between movable electrode 30 and drive electrode 235 and between lower fixed electrode 31 and movable electrode 30. Then, the position of the movable electrode 30, which is a movable portion, is displaced. The displacement of the position is detected by the lower fixed electrode 31, and self-diagnosis is made as to whether or not the movable electrode 30, which is a movable portion, is damaged.

Next, the operation will be described. Since the movable electrode 30 is formed in the second polysilicon layer 16, the lower fixed electrode 31 is formed in the first polysilicon layer 13, and the drive electrode 235 is formed in the third polysilicon layer 19,
A voltage is applied to the drive electrode 235, and an electrostatic force is generated between the movable electrode 30 and the drive electrode 235 and between the lower fixed electrode 31 and the movable electrode 30. Due to this electrostatic force, the position of the movable electrode 30, which is a movable part, is displaced. The movable electrode 30 generated by the displacement of the position and the lower fixed electrode 31 below the movable electrode 30
The lower fixed electrode 31 detects a change in capacitance between the lower fixed electrode 31.

As described above, according to the semiconductor acceleration sensor of the tenth embodiment, when a voltage is applied to drive electrode 235, the potential between movable electrode 30 and drive electrode 235 and the potential between movable electrode 30 and lower fixed electrode 31 become higher. The lower fixed electrode 31 detects the displacement of the movable electrode 30 caused by the electrostatic force, and can self-diagnose whether the movable electrode 30 is damaged. A sensor can be obtained.

Embodiment 11 FIG. FIG. 26 is a sectional view (a) and a plan view (b) showing a semiconductor acceleration sensor according to Embodiment 11 of the present invention.
Are drive electrodes formed on a part of the first polysilicon layer 13 and are formed separately from the lower fixed electrode 31. The same components as those in the first, seventh and tenth embodiments shown in FIGS. 1 to 4, 21 and 25 are denoted by the same reference numerals, and redundant description will be omitted.

In the semiconductor acceleration sensor according to the eleventh embodiment, a voltage is applied to drive electrode 335 to generate an electrostatic force between movable electrode 30 and drive electrode 335 and between lower fixed electrode 31 and movable electrode 30. Then, the position of the movable electrode 30, which is a movable portion, is displaced. The displacement of the position is detected by the lower fixed electrode 31 and the upper fixed electrode 34, and the self-diagnosis of the damage of the movable electrode 30 as the movable portion is performed.

Next, the operation will be described. The movable electrode 30 is formed in the second polysilicon layer 16, and the lower fixed electrode 31 and the drive electrode 335 are formed in the first polysilicon layer 13. The drive electrode 335 is formed separately from the lower fixed electrode 31. An upper fixed electrode 34 is formed on the third polysilicon layer 19. When a voltage is applied to the drive electrode 335, an electrostatic force is generated between the movable electrode 30 and the lower fixed electrode 31 or the upper fixed electrode 34, and the position of the movable electrode 30, which is a movable portion, is displaced by the electrostatic force. This displacement changes the capacitance between the electrodes, and both the lower fixed electrode 31 and the upper fixed electrode 34 detect the change in the capacitance.

As described above, according to the semiconductor acceleration sensor of the eleventh embodiment, when a voltage is applied to drive electrode 335, an electrostatic force is generated between movable electrode 30 and lower fixed electrode 31 or upper fixed electrode 34. However, by detecting the displacement of the movable electrode 30 caused by the electrostatic force by the lower fixed electrode 31 or the upper fixed electrode 34, the presence or absence of damage to the movable electrode 30 can be self-diagnosed. A sensor can be obtained.

Embodiment 12 FIG. 27 and 28 are cross-sectional views showing a semiconductor acceleration sensor chip according to Embodiment 12 of the present invention. In the drawings, reference numeral 36 denotes a lead frame, 37 denotes a wire bond, 39 denotes a semiconductor acceleration sensor, and 40 denotes a semiconductor acceleration sensor. A semiconductor acceleration sensor in which an integrated circuit such as a CMOS circuit is integrated, and a resin mold 38 seals the semiconductor acceleration sensors 39 and 40.

In the semiconductor acceleration sensor chip of the twelfth embodiment, the semiconductor acceleration sensor shown in the first to eleventh embodiments is packaged by sealing with a resin mold 38.

Next, the operation will be described. 27 (a) to (d) show the semiconductor acceleration sensor 39,
After the semiconductor acceleration sensor with integrated circuit 40 (FIG. 27, FIG. 28A) is adhered to the lead frame 36 (FIG. 27, FIG. 2).
8 (b)), the semiconductor acceleration sensors 39 and 40 are connected to the lead frame 36 (FIGS. 27 and 28 (c)).
Semiconductor acceleration sensor 3 connected to lead frame 36
9 and 40 are completely sealed with a resin mold 38 to form a small-sized, high-impact semiconductor acceleration sensor chip having an integral structure (FIGS. 27 and 28 (d)). The operations of the semiconductor acceleration sensors 39 and 40 are described in Embodiments 1 to 1.
1 has been described, and will not be described here.

As described above, according to the semiconductor acceleration sensor chip of the twelfth embodiment, the semiconductor acceleration sensors of the first to eleventh embodiments are integrally manufactured in a single package in a package, so that the package cost can be reduced. Thus, a semiconductor acceleration sensor chip having a small size and high impact resistance can be obtained.

[0089]

As described above, according to the first aspect of the present invention, the first insulating layer, the first polysilicon layer, the second insulating layer,
Since the second polysilicon layer, the third insulating layer, and the third polysilicon layer are configured as an integrated structure, and a part of the second polysilicon layer is configured as a movable part in the sealed gap, the size is small. It has a high impact resistance function, and has the effect of detecting the applied acceleration with high sensitivity.

According to the second aspect of the present invention, the first insulating layer, the first polysilicon layer, the first oxide film, the second insulating layer, the second polysilicon layer, the second dioxide film, the third insulating layer, and the The three polysilicon layers are sequentially manufactured in an integrated structure by a semiconductor microfabrication manufacturing process, the first oxide film and the second dioxide film are collectively removed by etching to form a void portion, thereby forming a movable portion, and finally, an etching hole. The semiconductor acceleration sensor is manufactured by encapsulating the semiconductor acceleration sensor by sealing the gap, thereby providing an effect of efficiently manufacturing the semiconductor acceleration sensor of an integral structure at a high yield.

According to the third aspect of the present invention, the semiconductor acceleration sensor and the integrated circuit are formed on the same semiconductor substrate to form a semiconductor acceleration sensor integrated with the integrated circuit.
The semiconductor acceleration sensor can be manufactured compactly and the detected output can be immediately and efficiently processed.

According to the present invention, the magnitude of the capacitance between the movable electrode and the fixed electrode is detected to detect the magnitude of the acceleration applied to the semiconductor acceleration sensor. Therefore, there is an effect that the applied acceleration can be detected with high sensitivity.

According to the fifth aspect of the present invention, the movable portion has two
Since the structure is configured to be supported by the two bridges, the effect of twisting of the movable portion can be reduced, and the magnitude of the acceleration applied to the semiconductor acceleration sensor can be detected with higher sensitivity.

According to the sixth aspect of the present invention, the left movable electrode and the right movable electrode are formed on the second polysilicon layer, and the left fixed electrode and the right fixed electrode are respectively formed in correspondence with these. Since the central portion is supported, the magnitude of the acceleration applied to the semiconductor acceleration sensor can be detected with higher sensitivity.

According to the seventh aspect of the present invention, since the four ends of the movable electrode are supported by the plurality of supporting portions, the magnitude of the acceleration applied to the semiconductor acceleration sensor can be further increased with high sensitivity. There is an effect that can be detected.

According to the present invention, the upper fixed electrode and the lower fixed electrode are formed in the third polysilicon layer and the first polysilicon layer corresponding to the upper and lower sides of the movable electrode, respectively. , Detecting the change in the magnitude of the capacitance generated between the movable electrode and the upper fixed electrode and between the movable electrode and the lower fixed electrode, and further increasing the magnitude of the acceleration applied to the semiconductor acceleration sensor. There is an effect that can be detected with sensitivity.

According to the ninth aspect of the present invention, since the diffusion resistance part is formed in a part of the movable part and the change in the resistance value of the diffusion resistance part is measured, the invention is applied to the semiconductor acceleration sensor. There is an effect that the magnitude of the acceleration can be detected with high sensitivity.

According to the tenth aspect, the diffusion resistance portion is formed as a thin portion thinner than the thickness of the second polysilicon layer other than the diffusion resistance portion, and the change in the resistance value of the diffusion resistance portion is measured. With such a configuration, the magnitude of the acceleration applied to the semiconductor acceleration sensor can be detected with high sensitivity.

According to the eleventh aspect, the lower fixed electrode is formed inside the first polysilicon layer, the movable electrode is formed inside the second polysilicon layer, and the lower fixed electrode is formed inside the third polysilicon layer. The upper fixed electrode is formed, and furthermore, the first polysilicon layer, the second polysilicon layer, and the third polysilicon layer are configured to diffuse impurities to form a wiring. A change in the magnitude of the capacitance generated between the movable electrode and the lower fixed electrode can be detected through the wiring, and the magnitude of the acceleration applied to the semiconductor acceleration sensor can be detected with high sensitivity.

According to the twelfth aspect of the present invention, the capacitance between the movable electrode and the fixed electrode generated by applying a voltage to the drive electrode formed apart from the fixed electrode in the first polysilicon layer. , The self-diagnosis can be performed by detecting the presence or absence of damage to the movable electrode, and there is an effect that the failure of the semiconductor acceleration sensor can be easily determined.

According to the thirteenth aspect of the present invention, a diffusion resistance portion is formed in the second polysilicon layer, and a voltage is applied to the fixed electrode as a drive electrode formed in the first polysilicon layer to apply a voltage to the diffusion resistance portion. Because it was configured to measure the resistance value of
The self-diagnosis can be performed by detecting the presence or absence of damage to the movable electrode, and there is an effect that a defect of the semiconductor acceleration sensor can be easily determined.

According to the fourteenth aspect of the present invention, a drive electrode is formed in the third polysilicon layer, and a movable electrode generated by applying a voltage to the drive electrode and the movable electrode formed in the first polysilicon layer. Since it is configured to detect a change in the capacitance between the fixed electrode and the fixed electrode, it is possible to detect whether or not the movable electrode is damaged, and to perform a self-diagnosis, which is advantageous in that a defect of the semiconductor acceleration sensor can be easily determined. is there.

According to the fifteenth aspect of the present invention, the lower fixed electrode, the movable electrode, the upper fixed electrode, and the wiring are formed by diffusing the impurities, and the wiring is further driven in the first polysilicon layer apart from the lower fixed electrode. An electrode is formed, and a change in capacitance between the movable electrode and the upper fixed electrode and between the movable electrode and the lower fixed electrode, which are generated by applying a voltage to the electrode, are detected. The self-diagnosis can be performed by detecting the presence / absence of the semiconductor acceleration sensor, and the semiconductor acceleration sensor can be easily determined to be defective.

According to the sixteenth aspect of the present invention, the semiconductor acceleration sensor or the semiconductor acceleration sensor and the integrated circuit are formed on the same semiconductor substrate, and the semiconductor acceleration sensor is connected to the lead frame via wire bonds, and Is covered with a resin mold and hermetically sealed to form an integral structure in the same package. Therefore, there is an effect that a semiconductor acceleration sensor chip having a small size and high impact resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a method of manufacturing the semiconductor acceleration sensor shown in FIG.

FIG. 3 is an explanatory view showing a method for manufacturing the semiconductor acceleration sensor shown in FIG.

FIG. 4 is an explanatory view showing a method of manufacturing the semiconductor acceleration sensor shown in FIG.

FIG. 5 is a sectional view showing a semiconductor acceleration sensor according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing a semiconductor acceleration sensor according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a semiconductor acceleration sensor according to a second embodiment of the present invention.

FIG. 8 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a third embodiment of the present invention.

FIG. 9 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a third embodiment of the present invention.

FIG. 10 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a third embodiment of the present invention.

FIG. 11 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a fourth embodiment of the present invention.

FIG. 12 is a sectional view showing a semiconductor acceleration sensor according to a fifth embodiment of the present invention.

FIG. 13 is a plan view showing a semiconductor acceleration sensor according to a fifth embodiment of the present invention.

FIG. 14 is a plan view showing a semiconductor acceleration sensor according to a fifth embodiment of the present invention.

FIG. 15 is a plan view showing a semiconductor acceleration sensor according to a fifth embodiment of the present invention.

FIG. 16 is an explanatory diagram showing a manufacturing process of the semiconductor acceleration sensor according to the fifth embodiment of the present invention.

FIG. 17 is a sectional view showing a semiconductor acceleration sensor according to a sixth embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a part of the method for manufacturing the semiconductor acceleration sensor according to the sixth embodiment of the present invention.

FIG. 19 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a seventh embodiment of the present invention.

20 is an explanatory diagram illustrating the method for manufacturing the semiconductor acceleration sensor illustrated in FIG.

21 is a sectional view and a plan view of the semiconductor acceleration sensor shown in FIG.

22 is an explanatory diagram illustrating the method for manufacturing the semiconductor acceleration sensor illustrated in FIG.

FIG. 23 is a sectional view and a plan view showing a semiconductor acceleration sensor according to an eighth embodiment of the present invention.

FIG. 24 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a ninth embodiment of the present invention.

FIG. 25 is a sectional view and a plan view showing a semiconductor acceleration sensor according to a tenth embodiment of the present invention.

FIG. 26 is a sectional view and a plan view showing a semiconductor acceleration sensor according to Embodiment 11 of the present invention.

FIG. 27 is an explanatory diagram showing a method for manufacturing the semiconductor acceleration sensor chip according to Embodiment 12 of the present invention.

FIG. 28 is an explanatory diagram showing a method for manufacturing the semiconductor acceleration sensor chip according to Embodiment 12 of the present invention.

FIG. 29 is a sectional view showing a conventional semiconductor acceleration sensor.

[Explanation of symbols]

1,11 semiconductor silicon substrate (semiconductor substrate), 2,1
2 First nitride film (first insulating layer), 3, 13 First polysilicon layer, 4, 15 Second nitride film (second insulating layer), 5,
16 second polysilicon layer, 5a, 24 movable part, 6,
18 Third nitride film (third insulating layer), 7, 19 Third polysilicon layer, 14 First oxide film, 17th dioxide film, 21
CMOS circuit part (integrated circuit), 22 Bipolar circuit part (integrated circuit), 23 ', 31 Lower fixed electrode, 23a
Left fixed electrode, 23b Right fixed electrode, 24b Bridge, 2
4c left movable electrode, 24d right movable electrode, 24f, 2
6, 30 movable electrode, 24 g support, 25, 34 upper fixed electrode, 27, 27 a to 27 d diffusion resistance, 29
Thin part, 33 wiring, 35, 235, 335 drive electrode, 36 lead frame, 37 wire bond, 38
Resin mold, 39, 40 semiconductor acceleration sensor, 1
71 void.

Claims (16)

[Claims] 1. A semiconductor substrate, a first insulating layer formed on a surface of the semiconductor substrate, a first polysilicon layer formed on a surface of the first insulating layer, and a surface of the first polysilicon layer A second insulating layer formed on the surface of the second insulating layer, a third insulating layer formed on the surface of the second polysilicon layer, the third insulating layer A third polysilicon layer formed on the surface of the layer,
The first insulating layer, the first polysilicon layer, the second insulating layer, the second polysilicon layer, the third insulating layer and the gap surrounded by the third polysilicon layer and sealed, the A semiconductor acceleration sensor in which a part of the second polysilicon layer is formed as a movable part. A first insulating layer formed on a surface of the semiconductor substrate, a first polysilicon layer formed on the first insulating layer,
Removing a part of the first polysilicon layer, forming a first oxide film on the first polysilicon layer and the first insulating layer,
Removing a part of the first oxide film, forming a second insulating layer on a surface other than the first oxide film on the first polysilicon layer, and forming a surface of the first oxide film and the second insulating layer; Flattened to be coplanar, forming a second polysilicon layer on the flattened first oxide film and the second insulating layer, removing a part of the second polysilicon layer, Forming a second dioxide film on the second polysilicon layer and the first oxide film, removing a part of the second dioxide film, and removing a third dioxide film on the second insulating layer, Forming an insulating layer, flattening the surfaces of the second dioxide film and the third insulating layer so as to be flush with each other, and forming a third poly over the flattened third insulating layer and the second dioxide film; Forming a silicon layer and etching a part of the third polysilicon layer on the second dioxide film; A movable part whose position is displaced in accordance with the acceleration to which a part of the second polysilicon layer is applied, by removing the first oxide film and the second dioxide film by etching through the etching hole. Forming a hollow portion so as to satisfy the following condition, and thereafter closing the etching hole with polysilicon. 3. The semiconductor acceleration sensor according to claim 1,
An integrated circuit formed on a semiconductor substrate of the semiconductor acceleration sensor and processing a signal corresponding to the magnitude of the applied acceleration output from the semiconductor acceleration sensor. 4. A movable electrode formed in a part of a movable part in a second polysilicon layer, and a fixed electrode formed in a part of a first polysilicon layer, wherein the movable electrode is fixed to the fixed part. 2. The semiconductor acceleration sensor according to claim 1, wherein the magnitude of the applied acceleration is detected based on a change in capacitance between the electrode and the electrode. 5. The semiconductor acceleration sensor according to claim 4, wherein an end portion of the movable portion is supported by two bridges. 6. A center portion of the second polysilicon layer is supported by a second insulating layer, and both ends of the second polysilicon layer are formed in a gap as a left movable electrode and a right movable electrode. 5. The semiconductor acceleration sensor according to claim 4, wherein a left fixed electrode and a right fixed electrode are respectively formed in the first polysilicon layer corresponding to the right movable electrode. 7. The movable electrode according to claim 4, wherein four end portions of the movable electrode are supported by a plurality of support portions arranged so as to surround the movable electrode and formed from the second polysilicon layer. Semiconductor acceleration sensor. 8. A movable electrode formed on a part of a movable part in the second polysilicon layer, a lower fixed electrode formed on a part of the first polysilicon layer at a position corresponding to the movable electrode, Having an upper fixed electrode formed on a part of the third polysilicon layer at a position corresponding to the movable electrode, between the movable electrode and the upper fixed electrode, and between the movable electrode and the lower fixed electrode. 2. The method according to claim 1, wherein the magnitude of the applied acceleration is detected based on a change in capacitance.
The semiconductor acceleration sensor as described in the above. 9. A movable resistance part formed by diffusing an impurity and a movable electrode in a part of the movable part in the second polysilicon layer, and is applied based on a change in the resistance value of the diffusion resistance part. 9. The apparatus according to claim 1, wherein the magnitude of the acceleration is detected.
Item 7. The semiconductor acceleration sensor according to Item 1. 10. The device according to claim 9, wherein the diffusion resistance portion is formed as a thin portion having a thickness smaller than a thickness of the second polysilicon layer where the diffusion resistance portion is not formed. Semiconductor acceleration sensor. 11. A movable electrode formed on a part of a movable part in the second polysilicon layer, a lower fixed electrode formed on a part of the first polysilicon layer at a position corresponding to the movable electrode, An upper fixed electrode formed on a part of the third polysilicon layer at a position corresponding to the movable electrode, and diffuses impurities into the first polysilicon layer, the second polysilicon layer, and the third polysilicon layer. The movable electrode, the upper fixed electrode and a wiring connected to the lower fixed electrode, the movable electrode and the upper fixed electrode,
2. The semiconductor acceleration sensor according to claim 1, wherein the magnitude of the applied acceleration is detected through the wiring based on a change in capacitance between the movable electrode and the lower fixed electrode. 12. A movable electrode formed in a part of a movable portion in a second polysilicon layer, a fixed electrode formed in a first polysilicon layer, and a fixed electrode formed in the first polysilicon layer. And a drive electrode formed by applying a voltage to the drive electrode to detect a change in capacitance between the movable electrode and the fixed electrode to determine whether the movable electrode is damaged. 2. The semiconductor acceleration sensor according to claim 1, having a self-diagnosis function for detecting. 13. A movable electrode formed in a part of a movable part in the second polysilicon layer and a diffusion resistance part formed by diffusing an impurity in a part of the movable part; And a self-diagnosis function of detecting whether or not the movable electrode is damaged by detecting a change in the resistance value of the diffusion resistance portion caused by applying a voltage to the fixed electrode. Item 2. A semiconductor acceleration sensor according to item 1. 14. A change in capacitance between the movable electrode and the upper fixed electrode caused by applying a voltage to the upper fixed electrode and a change in capacitance caused between the movable electrode and the lower fixed electrode are detected. 12. The semiconductor acceleration sensor according to claim 11, wherein the semiconductor acceleration sensor has a self-diagnosis function of detecting whether the movable electrode is damaged. 15. A movable electrode having a lower fixed electrode formed in a first polysilicon layer and a drive electrode formed separately from the lower fixed electrode, wherein a movable electrode generated by applying a voltage to the drive electrode and an upper electrode are provided. A self-diagnosis function for detecting whether or not the movable electrode is damaged by detecting a change in capacitance between the movable electrode and the lower fixed electrode and a change in capacitance between the movable electrode and the lower fixed electrode. Item 12. A semiconductor acceleration sensor according to item 11. 16. The method according to claim 1, further comprising:
A semiconductor acceleration sensor according to any one of 1;
A lead frame connected to the semiconductor acceleration sensor with a wire bond, and a semiconductor acceleration sensor chip in which the semiconductor acceleration sensor, the wire bond, and the lead frame are sealed with a resin mold.